1. Field
Disclosed subject matter is in the field of semiconductor fabrication and, more specifically, the fabrication of gate dielectrics for metal oxide semiconductor field effect transistors (MOSFETs).
2. Related Art
As the required thickness for conventional silicon dioxide gate dielectrics has decreased with advancing technology and smaller devices, gate oxide leakage has become unacceptable for standby power dissipation in low power parts, which is a key factor in differentiating among competitors for low power devices including most mobile devices. High-κ dielectrics have been used to produce an effective oxide thickness that is substantially lower than the physical thickness of the film itself and thereby achieve desirable performance characteristics without sacrificing static power dissipation and/or reliability. Hafnium dioxide (HfO2) is an example of a high-κ dielectric material desirable for its comparatively high dielectric constant and its relative stability in a manufacturing environment. It is known, however, that MOSFETs employing conventional HfO2 gate dielectrics often suffer from threshold voltage (Vt) instability, relatively lower mobility (Gm), and degraded positive bias temperature instability (PBTI) reliability.